Correct option is D
A
synchronous motor can be used to improve the power factor of an electrical system when operated at no load with over-excitation. Here's how it works:
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Over-Excitation: When a synchronous motor is over-excited (meaning the field excitation is higher than the level required to produce a unity power factor), it draws leading reactive power (VARs) from the system. This leading reactive power can offset the lagging reactive power caused by inductive loads, thereby improving the overall power factor of the system.
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No Load Operation: Operating the synchronous motor at no load ensures that it doesn't draw significant active power from the system, allowing it to primarily function as a reactive power compensator (also known as a synchronous condenser).
